MAGETWO-38645: Add Sliding Panel for Order Summary block on Checkout

- CR changes

app/code/Magento/Checkout/view/frontend/web/template/authentication.html

@@ -7,7 +7,7 @@
 <div class="authentication-wrapper" data-block="authentication" data-bind="visible: isActive()">
     <button
         type="button"
-        class="action-auth-toggle"
+        class="action action-auth-toggle"
         data-trigger="authentication">
         <span data-bind="text: $t('Sign In')"></span>
     </button>

app/code/Magento/Checkout/view/frontend/web/template/onepage.html

@@ -20,7 +20,7 @@
         <span class="estimated-price">$100.00</span>
     </div>
     <div class="minicart-wrapper">
-        <button type="button" class="action showcart action-showcart" data-toggle="opc-summary">
+        <button type="button" class="action showcart" data-toggle="opc-summary">
             <span class="counter qty">
                 <span class="counter-number">6</span>
             </span>
@@ -29,7 +29,7 @@
     <!-- Temp MAGETWO-36025 markup
     <button
         type="button"
-        class="action showcart action-showcart"
+        class="action showcart"
         data-toggle="opc-summary">
         <span data-bind="text: $t('View order summary')"></span>
     </button>-->

app/design/frontend/Magento/blank/Magento_Checkout/web/css/source/module/checkout/_authentication.less

@@ -118,11 +118,14 @@
         top: 100%;
         transform-origin: 0 0;
         transform: scale(1,0);
-        transition: transform linear .1s;
+        transition: transform linear .1s, visibility 0s linear .1s;
+        visibility: hidden;
         width: 100%;
         &._show {
             .css(z-index, @dropdown-list__z-index);
             transform: scale(1,1);
+            transition: transform linear .1s, visibility 0s linear 0s;
+            visibility: visible;
         }
     }
     .authentication-wrapper {

app/design/frontend/Magento/blank/Magento_Checkout/web/css/source/module/checkout/_order-summary.less

@@ -157,8 +157,9 @@
 }
 
 //
-//    Desktop
-//--------------------------------------
+//  Desktop
+//  _____________________________________________
+
 .media-width(@extremum, @break) when (@extremum = 'min') and (@break = @screen__m) {
     .opc-summary-wrapper {
         .modal-header {

app/design/frontend/Magento/luma/Magento_Checkout/web/css/source/module/checkout/_estimated-total.less

@@ -34,10 +34,12 @@
         }
 
         .minicart-wrapper {
-            .action-showcart {
-                .button-reset();
-                &:before {
-                    .css(color, @primary__color);
+            button {
+                &.action.showcart {
+                    .button-reset();
+                    &:before {
+                        .css(color, @primary__color);
+                    }
                 }
             }
         }